ASK1调节的p38MAPK通路在糖尿病视网膜病变发病中的作用研究

Previous studies have found that a persistent low-grade aseptic inflammation occurs in the pathogenesis of diabetic retinopathy (DR) and showing an association of inflammatory factors and the progression of DR. Recent studies have demonstraed that high glucose sustains NLRP3 up-regulation in the retina of diabetic rats , but the mechanism of NLRP3 inflammasome activation in the pathogenesis of DR is still unclear. Recently, our studies found that there is a sustained high phosphorylated apoptosis signal-regulating kinase 1 (ASK1) expression in the retina of diabetic rats. ASK1 is located the upstream of p38 MAPK, however, ASK1 regulating p38 MAPK signalling pathway activate NLRP3 inflammasome in the diabetic retinal vascular injury is not clear. Therefore, our study is designed to, firstly, explore the effect of ASK1 in the apoptosis of human retinal microvascular endothelial cells (HRMECs) incubated in high glucose in vitro and the retina injury of diabetic rats in vivo; secondly, clarify the association of NLRP3 inflammasome up-regulation and ASK1/p38 MAPK activation in high glucose; further, by intervention study in vitro and vivo, reveal that the ASK1 maby be potentially effective therapeutic target for DR. In conclusion, the novel findings would highlight the potential role of ASK1 in the pathogenesis of DR with low-grade inflammation, and our results may provide scientific basis for the prevention and treatment of DR.

既往研究发现，糖尿病视网膜病变（DR）长期存在低度炎症，炎症因子与DR发病及进展有关。研究发现在糖尿病大鼠视网膜组织中NLRP3炎症小体持续高表达,而NLRP3炎症小体在DR发病中如何被激活机制不清晰。最近，本课题组研究发现，磷酸化凋亡信号调节激酶l（ASK1）在糖尿病大鼠视网膜组织中表达上调。ASK1位于p38MAPK的上游，但ASK1调节的p38MAPK通路在高糖刺激下是否激活NLRP3炎症小体机制不明。为此，本课题首先通过体内外研究揭示ASK1在高糖孵育的视网膜血管内皮细胞凋亡及糖尿病大鼠视网膜血管损伤中的作用及分子机制；其次，阐明高糖环境下NLRP3炎症小体的活化可能与ASK1/p38MAPK通路激活有关；进一步以ASK1基因为靶标进行体内外干预，揭示ASK1可能是DR治疗潜在的有效靶点。本课题研究的结果可丰富人们对DR低度炎症发生等机制的认识，为DR临床防治提供理论和实验依据。

既往研究发现，糖尿病视网膜病变（DR）长期存在低度炎症，炎症因子与DR发病及进展有关。本研究应用DR动物模型和人视网膜血管内皮细胞模型，探讨了ASK1在DR发病中的作用及其分子机制研究。首先，我们通过体内外研究探讨ASK1调节的p38MAPK通路在DR异常视网膜血管形成中的作用研究。研究结果表明：DR诱导炎症反应和微血管增生，NLRP3参与DR介导的炎症反应和进展，促进炎症相关细胞因子的表达，且NLRP3促进视网膜微血管内皮细胞管的形成和血管生成；ASK1/p38信号轴调控了DR中NLRP3介导的异常视网膜血管形成。其次，我们探讨了ASK1引起DR中视网膜微血管内皮细胞凋亡的机制研究。研究结果表明：体内外研究均显示人视网膜血管内皮细胞凋亡增加，高糖诱导的细胞凋亡主要以内质网应激依赖性的方式发生；通过shRNA或特异性抑制剂NQDI-1抑制ASK1可减轻高糖诱导的凋亡；ASK1促进DR中ER应激相关蛋白的表达。最后，我们探讨了p38促进DR中微血管生成的机制研究。研究结果表明：体内外研究显示RUNX1在DR中高表达，p38通过上调RUNX1在DR中的表达促进视网膜异常微血管生成。因此，本研究的开展揭示了ASK1/p38可能是DR治疗的有效靶点，丰富了人们对DR低度炎症发生等机制的认识，为DR临床防治提供理论和实验依据。